Nickel base superalloys have been extensively investigated for many years, and there are many patents which describe various alloy compositions. See, for example, U.S. Pat. No. 4,402,772 and the patents discussed therein.
In U.S. Pat. No. 4,402,772, it is stated that nickel base superalloys typically contain chromium in levels of about 5-15 weight percent, primarily for oxidation resistance; additionally it is stated that nickel base superalloys typically contain cobalt in levels of about 5-15 weight percent.
One example of a nickel base superalloy having a composition outside of the typical range of U.S. Pat. No. 4,402,772 is a cobalt free nickel base superalloy, described in U.S. Pat. No. 4,222,794. Its nominal composition, on a weight percent basis, is 5.2 Cr, 5.4 Al, 1.1 Ti, 2.0 Mo, 4.9 W, 6.4 Ta, 3.0 Re, 0.4 V, with the balance Ni. U.S. Pat. No. 4,116,723 describes a cobalt free nickel base superalloy whose nominal composition is 9 Cr, 5 Al, 2 Ti, 12 W, 1 Cb, with the balance nickel.
U.S. Pat. No. 4,055,447 describes a chromium free nickel base superalloy. The alloy has aligned gamma prime Ni.sub.3 Al reinforcing fibers to enhance its strength. The alloy composition is, on a weight percent basis, 6-9 Al, 5-11 Ta, 0-10 Co, 0-6 V, 0-6 Re, 2-6 W, with the balance nickel. The sum of the atomic percentages of (Al+Ta) must be within the range of 19-22, and the ratio of the atomic percentages of Ta: (Al+Ta) must be within the range of 0.12-0.23.
U.S. Pat. No. 4,045,255 describes a chromium free nickel base superalloy which contains aligned NiAl reinforcing fibers. The broadest alloy composition is, on a weight percent basis, 8.5-14.5 Al, 5-15 W, 0-35 Co, with the balance nickel. The alloy optionally contains up to 0.5 Y, up to 3 Ta, and up to 4.5 Re in substitution for a portion of W.
U.S. Pat. No. 4,292,076 describes a chromium free nickel base superalloy which contains aligned carbide reinforcing fibers. The broadest alloy composition is, on a weight percent basis, 0-10 Al, 3-15 Ta, 0-20 Co, 0-20 Cr, 0-7 V, 0-9 Re, 0-20 W, 0-10 Mo, 0-0.8 Ti, 0.1-1 C, 0-3 Cb, 0-3 Hf, 0-1.5 Zr, with the balance Ni.
U.S. Pat. No. 3,793,010 describes a nickel base superalloy which contains aligned delta Ni.sub.3 (Cb, Ta) fibers. One preferred composition is, on a weight percent basis, 73 Ni, 21 Cb, 6 Cr. Another composition is 68 Ni, 21 Cb, 9 Cr, 2 Al.